1. Technical Field
The present invention relates to a climate control system and method, and more particularly a climate control strategy utilizing vehicle occupant comfort level settings to optimize fuel economy.
2. Background Art
Automatic climate control is increasingly prevalent in vehicles today. In some vehicles, a driver merely chooses a temperature setting through a climate control head unit, and a control system operates a climate control system to achieve the desired temperature. The climate control system may control the functions of a fan—e.g., on/off and fan speed—and an air conditioning (A/C) system. Such a climate control system may also control the position and movement of various air dampers, or air flow doors, to control movement of air through an evaporator core or a heater core, the recirculation of air through the vehicle, the intake of fresh air, or some combination thereof.
Conventional automatic temperature control allows users to set extreme temperature set points often resulting in significant fuel economy penalties. For example, an occupant may set the automatic temperature control at the extreme low setting in warm ambient conditions while simultaneously opening vehicle windows. In doing so, the air conditioning system uses an air conditioning compressor and a condenser to effectuate cooling of a passenger cabin of the vehicle. However, operation of the air conditioning compressor uses a relatively large amount of energy. Meanwhile, some of the cooling capacities of the A/C system are lost when the windows are open.
The lower the automatic temperature setting, the harder the compressor and a heating, venting and air conditioning (HVAC) blower must work to attain the extreme setting. In the case of a hybrid electric vehicle (HEV), operation of an electric compressor often necessitates starting the engine to ensure that the battery is not over-discharged. One of the benefits of an HEV is the fuel savings achieved by driving the vehicle using electric motor power, while maximizing the time the engine is shut down. Thus, inefficient operation of the climate control system can offset some of the benefits gained by driving an HEV.
Accordingly, a need exists for a system and method for vehicle climate control that strikes a balance between meeting the comfort requirements of vehicle occupants and minimizing the overall power consumed by the climate control system.